1. Field of the Invention
The present invention relates to finishing machines for concrete and particularly to blades which allow poured and partially dried concrete to be properly finished with a smooth surface. More particularly, the present invention relates to attachments to pre-existing trowel machines which allow the trowel machines to be converted into grinding machines thereby allowing the trowel machine to grind hardened concrete to a smooth finish.
2. Description of the Prior Art
In pouring wet concrete, several steps are required to insure a smooth concrete surface finish after the concrete has partially dried. When the concrete is still in semi-fluid form, it is initially screeded through the use of a screed board or long wooden plank. Screeding is required to bring the wet concrete surface to a roughly equal height. Once the concrete is initially set at this height, the surface of the concrete is then treated with a float. The floating operation is used to settle large stones, smooth out the surface of the wet concrete and settle the larger stones in the concrete below the surface. After the float operation is performed, the concrete has partially dried and the freshly poured concrete may be troweled in order to bring the surface to a smooth finish.
Utilizing a trowel machine with a plurality of blades, the surface of the concrete which is in a partially dried condition is contacted by the rotating blades of the machine and produces a smooth finish surface on the concrete which is free of bubbles and also allows for evaporation of water which may rise to the surface. However, troweling needs to be completed prior to the concrete becoming too hard. Once the freshly poured concrete has hardened, the troweling machine and its corresponding flat blades will not sufficiently smooth the concrete surface. If the freshly poured concrete has hardened to such an extent that the trowel blade or troweling machine will not properly work the concrete surface, a grinding stone is utilized to adequately smooth the concrete. A completely separate machine is utilized for grinding the surface and these machines contact the surface of the poured concrete with a grinding stone. A grinding machine operates to automatically smooth the surface with these rough grinding stones and the machine design has historically been different from the troweling machine due to the moving characteristics of the grinding stone and the like. As a result, the concrete finisher must have both a troweling machine and a grinding machine nearby in case the concrete hardens to such an extent that the trowel machine will not adequately smooth the surface of the poured concrete. It is therefore desirable for the concrete finisher to have on hand an apparatus allowing the conversion of a troweling machine to a grinding machine so that the overhead of having the two aforementioned machines is not necessary.